Who will save the night sky?
If you travel to one of the darkest places on Earth, you can see one of the last great things completely unaltered by humans: the entire night sky.
But increasingly, even in the darkest places on Earth (which are vanishingly rare themselves), humankind is beginning to interfere with this primordial view. The unimpeded view of the night sky is being lost, and quickly.
In their quest to provide global broadband internet access to remote places, satellite companies are launching small constellation satellites into orbit close to the Earth so that the internet connection doesn’t have too long of a delay.
In the beginning of 2020, Elon Musk’s SpaceX had launched 240 small satellites into space as part of its Starlink internet service; now it has around 1,300. And more are planned to launch, from SpaceX, and from competitors like the UK-based OneWeb. SpaceX alone already has permission to launch 12,000 satellites, with dreams of launching a total of 30,000 one day.
At this rate, there’s little in the way of a future where you look up and just see the sky crawling. But particularly painful is the situation for astronomers. When the satellites cross into the view of their observatories, it can ruin the images. The effect of the satellite constellations is like painting graffiti on a World Heritage Site. But not just graffiti in one particular location — graffiti that can be seen the world over.
Last week, the International Astronomical Union presented a brief version of a report on the impact of these satellites to a subcommittee of the UN Committee on the Peaceful Uses of Outer Space (COPUOS), along with some recommendations to mitigate the loss of unobstructed night sky.
But some astronomers fear they’ve already lost the battle. “The mechanisms in [international] law that might have allowed us to avoid this, those wheels turn so slowly that by the time we would get to any consensus on a policy solution, this is all going to be over,” says John Barentine, an astronomer and the director of public policy at the International Dark Sky Association, who helped author the IAU report. “I just think that it’s a numbers game that astronomy probably cannot win.”
Here’s why astronomers are so glum, and why they’re so motivated to fight anyway.
The satellites block the view of telescopes
Starlink and its competitors are in pursuit of a goal with merit: to connect more of the world, particularly remote, rural places, to the internet. Too many places are cut off from broadband access, and therefore cut off from the modern world and economy. This increased connectivity could even help scientists do their work in more places on Earth. (It’s not completely altruistic, however: These companies plan on charging for this internet.)
But it comes with a cost. Because these satellites are so close, and reflective, they are often visible to the unaided human eye. But even if they were dimmed significantly, they would still be visible to powerful telescopes used in astronomy, should a satellite cross their path. When a satellite comes into view of a telescope, it can ruin the image — or at least provide more work for the astronomers to correct for it. It’s also a problem of numbers.
“The number of satellites orbiting the Earth is about to increase by about an order of magnitude,” Barentine says. “And that makes it increasingly likely that science will be lost.”
Beyond appearing as just streaks in images or distinct lights in the sky, the satellites can also introduce a diffuse glow into the background darkness of the night sky. This has already begun.
Barentine was part of a study that found that even before SpaceX launched a single satellite, all of humanity’s space objects likely increased the background brightness of the night sky by 10 percent compared to the pre-space age. It’s not enough to notice from the ground, Barentine says. But that could change. “That 10 percent figure is kind of a lower limit, in a sense, because as more objects are launched, it should steadily rise.”
That could fundamentally change our collective human experience of the night sky. This isn’t light pollution as we commonly think of it (i.e., the glow of city lights dimming our view of the sky and making many stars unseeable in populated areas).
Instead, it’s about satellites invading the skies — even the darkest places on Earth untouched by light pollution — particularly near the hours of dusk and dawn, when they are more likely to catch the light of the sun. And that’s exactly the critical time astronomers use to look for near-Earth asteroids that could potentially collide with our planet.
Some scientific ventures will be impacted more than others. Most notably, the Vera Rubin Observatory. It’s an observatory under construction in Chile with a huge field of view: Its mirrors will be able to capture an area of the sky 40 times the size of the full moon, and spot objects 10 million times fainter than the human eye could see. The Vera Rubin Observatory is built to take in huge swaths of the sky at once, and look at it holistically. That wide view, however, means that more satellites can cross into its gaze.
Similarly, the wide field of view problem will also impact hobbyists who like to take pictures of the night sky with long exposures. (Observatories with a narrower field of view might have an easier time just not operating when a satellite is predicted to come across their sensors.)
The UN works slowly, and without much bite
The IAU recommendations to the UN basically rest on the argument that satellite operators and the regulatory agencies that oversee them (like the US Federal Communications Commission) should be considering impacts to astronomy and the night sky, and come up with some general guidelines for how bright is too bright.
If the subcommittee endorses the report and its recommendations, it goes to a full meeting of COPUOS in August, which could decide to forward the recommendations to the member states of the committee. If this process sounds like it lacks teeth, well, it does. This wouldn’t have the power of an international law (for that, the spacefaring nations would have to renegotiate the 1967 Outer Space Treaty).
“It’s not really a policy agenda, but it’s sort of a tone, like the world got together, considered this problem, decided it was significant, came up with a series of recommendations to try to minimize it,” Barentine says. It’s a “sense that we’ve identified a problem and proposed some solutions.”
Barentine recognizes how little leverage the astronomy community has.
The biggest problem isn’t with SpaceX or OneWeb, per se. SpaceX in particular has been working with the astronomy community to darken the appearance of their satellites (though the IAU report finds SpaceX’s tweaks “do not achieve the recommendation brightness goals” — they’ll still be visible to the unaided eye, and still will interfere with observatories and astrophotography). Notably, while SpaceX works on the problem, they’re still contributing to it. “They were unwilling to hold launches until the problem was solved,” Barentine says.
In a recent FCC approval of SpaceX orbital operations, the FCC notes that SpaceX does not need to conduct a National Environmental Policy Act (NEPA) assessment of its operations. (This would require assessing the environmental impact of the satellites; stemming from a 1986 FCC decision, satellites are exempt from NEPA.) The FCC writes it “will continue to monitor this situation” when it comes to astronomy interference.
SpaceX aside, the biggest problem is that there are no international regulations for how satellites look to us on Earth. SpaceX is “not legally obligated to do a thing in listening to the astronomers’ concerns,” Barentine says. They’re doing it of their own volition. Another company, in another country, could be more brazen with sending up even brighter satellites. That’s why the IAU went to the UN: They hope to achieve an international consensus.
The future of tens of thousands of microsatellites in the sky is coming, and it is bleak
In a future where there are tens of thousands of microsatellites in the sky, “There’ll be nowhere where you can take [the Vera Rubin] and point it without having one of them in the field of view,” Tony Tyson, a University of California Davis astronomer and physicist who works on the Vera Rubin Observatory told me in December 2019. I just emailed him asking if there have been breakthroughs in mitigating the problem since. “No changes, and no major mitigations,” he writes.
There are a lot of other potential concerns about so many satellites in the sky. One is space debris. When a satellite breaks down in space, it just stays up there as junk until gravity pulls it back down to Earth. Already, a Starlink satellite and one from OneWeb had a near collision.
We lose intangible things when we alter the night sky. “Satellite constellations … strike at the core of humanity’s scientific and cultural relation to the night sky, affecting millennia-old sky traditions and cultural practices across all nations around celestial cycles and the night sky,” physicists Aparna Venkatesan, James Lowenthal, Parvathy Prem, and Monica Vidaurri write in Nature Astronomy. “Treating space as the ‘Wild West’ frontier that requires conquering continues to incentivize claiming by those who are well-resourced.”
Instead of the Wild West, they argue, we should think of the night sky “as an ancestral global commons,” containing “the heritage and future of humanity’s scientific and cultural practices.”
It’s not currently being treated that way.
“The fact that one person, or one company, can take control and completely transform humans’ experience of the night sky, and not just humans, but every organism on Earth … that seems profoundly wrong,” Caitlin Casey, a University of Texas Austin astronomer, told me in 2020.
Sadly, it’s still happening.